A method of establishing data communication between a data transmitting device and one or more data receiving devices and the apparatus therefor are provided in accordance with the teachings of the present invention. One of a predetermined number of data transmitting devices is selected to transmit data...http://www.google.com/patents/US3824334?utm_source=gb-gplus-sharePatent US3824334 - Data communications network

A method of establishing data communication between a data transmitting device and one or more data receiving devices and the apparatus therefor are provided in accordance with the teachings of the present invention. One of a predetermined number of data transmitting devices is selected to transmit data information. The capability of each of a predetermined number of data receiving devices to receive data information is determined and one or more of said predetermined number of data receiving devices is selected to receive data information. The data transmitting device selected to transmit data information is enabled to commence data information transmission and the data information received therefrom is transmitted to those data receiving devices selected to receive and capable of receiving data information. Indications of the selection of data transmitting and data receiving devices are provided as well as indications of the selection of data receiving devices not capable of receiving data information. The transmission of data information to a data receiving device that is not capable of receiving data information although said data receiving device has been inadvertently selected, is prevented.

[57] ABSTRACT A method of establishing data communication between a data transmitting device and one or more data receiving devices and the apparatus therefor are provided in accordance with the teachings of the present invention. One of a predetermined number of data transmitting devices is selected to transmit data information. The capability of each of a predetermined number of data receiving devices to receive data information is determined and one or more of said predetermined number of data receiving devices is selected to receive data information. The data transmitting device selected to transmit data information is enabled to commence data information transmission and the data information received therefrom is transmitted to those data receiving devices selected to receive and [56] References Cited capable of receiving data information. Indications of UNITED STATES EN V the selection of data transmitting and data receiving 2,843,660 7/1958 Franklin et al. 179/4 devices are as mdcatlons of the F" 3,098.1 19 7/1963 Lemelson 178/DlG. 22 lemon data reqelvmg devlces Papable of 3,376,509 4/1968 Willcox et al. 179/2 DP mg data mformation. The transm1ss1on of data lnfor- 3,549,809 12/1970 Stehr 179 2 DP mation to a data receiving device that .is not capable 3,592,962 7/1971 Matthews et a1. 178/D1G. 23 of receiving data information although said data re- 3,597,544 8/1971 Kennedy 179/2 DP ceiving device has been inadvertently selected, iS prevented. Primary Examiner-Howard W. Britten 33 Claims, 8 Drawing Figures ,27 39 40 25 l'lg Stcllion Selectors E17 J a V l 2 34 5 i u 1 2 3 5 e 7 a 9 1o M I M ALT use I m FA U 1 1o 9 a 7 s i '2" 2 2 2 H2 M3Q 3/ 3a 33' 34 55 36 37 36M 2 |1 U A A 1 1 w l l l i 73 PM /5 /s 1 1? 1 /a i /9 P20 i z/ 22 l 1 1 1 1 1 i 1 1 I 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 FAX FAX FAX FAX FAX FAX FAX FAX FAX FAX l 2 3 4 6 7 8 9 IO l 3 4 5 6' 8 9 l0 l2 PATENTED JUL] 51m SHEET 1 [1F 6 A A A A A A A A A A A o m m b w m w m N A X5 X3 x 5t 5t xi 52 5E xi 5: AA. AA A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A ww A & A Qm Q 9 A S Q 3 A Q A A A A A A A A A A A mm km m mm $6M mm R mm mm mm ww w hm an: N A A A A A WWI E i 2o 33 WE 20w m z z 2 m w A. w m A m N 32cm ucmw 3 3m 22m A A m vm m A U flmkzfizwm 8: H A A mm S mm kw mm INVENTORS Charles L. Jacobson John Tombert ATTORNEYS PATENTED L 1 61974 saw 6 OF 6 ATTORNEYS 1' DATA COMMUNICATIONS NETWORK This invention relates to data communication networks and in particular, to a method of and apparatus for establishing communication between one of a predetermined number of data transmitting devices andone or more of a predetermined number of data receiving devices.

In the field of data communications it is often desirable that a single central station be capable of communicating with any one of a predetermined number of remote stations. For example, in conventional computer time sharing systems, a general purpose digital computer is readily utilized for two-way communication by individual subscribers thereto, which subscribers may be situated at distinct locations. In another example, telemetry data systems have been developed to enable a plurality of remotedata sources to transmit data to a centralized data location. Unfortunately, data communication systems of the types just described do not readily permit the transmission of data from a central location simultaneously to a plurality of remote locations. Furthermore, these systems are usually not provided with the capability of providing data communication between remote locations. Also, the transmitting and receiving stations of prior art communication systems, such as the aforementioned telemetry data systems, are usually chosen in a predetermined manner and are not adapted to be randomly selected. In addition, the requisite communication paths extending between remote locations and a central station are notoriously expensive to construct and to maintain.

Conventional facsimile transmission systems heretofore utilized in the prior art suffer from disadvantages that are analogous to those described with respect to other data communication systems. Hence, although facsimile information may be expeditiously transmitted between two facsimile transceivers, it has heretofore been impractical to transmit facsimile information simultaneously to a plurality of facsimile transceivers. The manner in which business is transacted today requires the prompt transmission of data, and more particularly facsimile information, to a plurality of stations. Moreover, many organizations have numerous office locations that are geographically dispersed throughout the country and throughout the world. It is often desirable to rapidly transmit documents to a plurality of these offices from a central office and to receive documents therefrom. Furthermore, it is frequently necessary to enable an operator stationed at a central office to regulate the transmission of documents between remote offices.

In an attempt to accomplish the foregoing, the prior art has developed facsimile broadcasting systems wherein a central location may broadcast facsimile information to a plurality of remote locations through radio transmission. It is readily apparent that such facsimile broadcasting systems are relatively complex, expensive and limited in the distance over which a successful transmission may obtain. Accordingly, these facsimile broadcasting systems have proven to be impractical for facsimile communication with remote office locations as contemplated by perceptive and innovative businessmen of today.

In recent years, much progress has been made in transmitting facsimile information over conventional telephone lines. It is manifest that a public telephone system is a vast system of existing communication paths which may be readily adapted for inexpensive facsimile transmission between remote office locations. Hence, the public telephone system exhibits the potential of providing communication paths between a plurality of remote office locations that may be randomly selected from a central location. Accordingly, the prompt transmission of data necessary to the efficient and proper functioning of most organizations may be readily effected through the telephone system.

Therefore, it is an object of the present invention to provide a method of and apparatus for establishing communication between a data transmitting device and one or more data receiving devices.

It is another object of the present invention to provide a method of and apparatus for transmitting data from a central location to one or more remote locations.

his a further object of this invention to provide a method of and apparatus for establishing a communication channel between a remote location and a central location.

Yet another object of this invention is to provide a method of and apparatus for providing communication channels between a remote data transmitting device and one or more remote data receiving devices.

An additional object of this invention is to provide a method of and apparatus for enabling an operator at a central location to randomly establish plural communication channels between transmitting and receiving devices irrespective of the particular location of said devices.

Another object of the present invention is to provide a method of and apparatus for affording communication between randomly selected data transmitting and receiving devices via conventional telephone lines.

Still another object of this invention is to provide a facsimile braodcasting system including a plurality of remote facsimile transceivers and a local facsimile transceiver wherein facsimile information may be communicated therebetween.

It is a further object of the present invention to provide a manually operable switching system for establishing data transmission channels between randomly selectable devices.

Various other objects and advantages of the invention will become clear from the following detailed description of an exemplary embodiment thereof and the novel features will be particularly'pointed out in connection with the appended claims.

In accordance with this invention, a method of establishing communication between a data transmitting device and one or more data receiving devices, and the apparatus therefor, is provided wherein one of a plurality of predetermined data transmitting devices is selectedto transmit data; the capability of each of a plurality of data receiving devices to receive data is determined and one or more of the data receiving devices is selected to receive data; the data transmitting device selected to transmit data is supplied with an enabling signal to commence data information transmission; and the data information transmitted thereby is relayed to those data receiving devices selected to receive and capable of receiving data infonnation. An indication is provided when a data receiving device not capable of receiving data information is erroneously selected to receive.

y The invention will be more clearly understood by the reference to the following detailed description of an exemplary embodiment thereof in conjunction with the accompanying drawings in which:

FIG. 1 is a representative diagram of manually operable apparatus that may be utilized in accordance with the present invention;

FIG. 2 is a block diagram of the electrical apparatus in accordance with the present invention;

FIG. 3 is a block diagram of a portion of one of the blocks illustrated in FIG. 2;

FIG. 4 is a block'diagram of another portion of one of the blocks illustrated in FIG. 2;

FIG. 5 represents in partial schematic and partial block form some of the blocks illustrated in FIG. 2;

FIG. 6 is a logic circuit of the blocks illustrated in FIG. 3;

FIG. 7 is a logic circuit representing some of the blocks illustrated in FIG. 4; and

The present invention finds ready application in a data communication system such as a telemetry system, a computer communication system, a facsimile system or the like. For the purpose of explanation, and to facilitate the ready understanding thereof, the instant invention will be described with reference to a facsimile communication system including a plurality of remote facsimile transceiverscapable of transmitting and receiving facsimile information and a local facsimile transceiver capable of transmitting and receiving facsimile information. Nevertheless, it should be clearly understood that the present invention is not solely limited for use in a facsimile communication system. Hence, other conventional data transceivers or data transmitting and data receiving devices may be utilized in cooperation with the present invention.

Referring now to the drawings, and in particular to FIG. 1, there is illustrated a representation of a manually operable switching system in accordance with the present invention which comprises station selecting means 1, a local facsimile transceiver 2 and a plurality of remote facsimile transceivers 3-12. The local facsimile transceiver 2 is adapted to transmit and receive facsimile information and is directly coupled to station selecting means 1 by conventional electrical connecting means. Each of the remote facsimile transceivers 3-12 is similar to the local facsimile transceiver 2 and is coupled to the station selecting means 1 via individual telephone lines 13-22. It will soon be seen that each of the telephone lines 13-22 may comprise telephone lines leased from the public telephone system and therefore permanently dedicated for use between an associated one of the remote facsimile transceivers and the station selecting means 1. Alternatively, each of the telephone lines may be seized in the conventional manner for transmission between an associated one of the remote facsimile transceivers and the station selecting means 1 by the dialing of an appropriate number. Hence, a telephone line may be seized by an operator at the station selecting means location or by an operator at a remote facsimile transceiver location. In the following description, it will be assumed that telephone lines 13-20 are leased-telephone lines and telephone lines 21 and 22 are conventional subscriber telephone lines. Accordingly, facsimile transceivers 3-10 may be coupled to leased telephone lines 13-20 by any conventional coupling means such as the coupling means described in copending US. Pat. applicationSer. No. 165,455 filed by the inventor of the present invention on even dateherewith and assigned to Xerox Corporation, the assignee of the instant invention. Station selecting means 1 may be coupled to leased telephone stood that any convenient number of remote facsimile transceivers may be used with the present invention.

Station selecting means 1 is adapted to establish a transmission path between one of the facsimile transceivers 2-12 and one or more of the remaining facsimile transceivers in accordance with the manual operation thereof. FIG. 1 illustrates a typical front panel that is included in the apparatus in accordance with the present invention and may be operated by a suitably skilled operator-to effect the aforementioned transmission path. Although a description of FIG. 1 will not serve to explain the functions performed by the electrical circuitry comprising station selecting means 1, it will be seen that an understanding of the functions of the illustrated front panel will result in an appreciation of the advantages offered by the present invention. The illustrated front panel includes a START switch 23, a POWER ON switch 25, receive station selecting means 27, transmit station selecting means 39 and In Use indicating means 40. START switch 23 may be a conventional toggle switch, a push button switch,.or the like. In addition, the START switch 23 may be constructed to include a suitable visual indicator such as a lamp whereby closing of the START switch 23 serves to energize the associated visual indicator. POWER ON switch 25 is similar to START switch 23 and also includes a suitable visual indicator such as a lamp. Accordingly, the closing of POWER ON switch 25 serves to energize the associated visual indicator. Receive station selecting means 27 is comprised of a plurality of switches 28-37, each being similar to the START switch 23. Each of the switches 28-37 is associated with a remote facsimile transceiver 3-12, respectively. In addition, receive station selecting means 27 includes a further switch 38 associated with local facsimile transceiver 2. The switch 38 is also similar to START switch 23. Each of the receive station selecting switches 28-38 is associated with asuitable visual indicator such as a lamp. In addition, each of the receive station selecting switches 28-38 is associated with audio indicating means that is actuated upon the erroneous closing of a receive station selecting switch. EOM reset switch 24 is similar to START switch 23 and is adapted to be manually activated upon the termination of a facsimile information transmission. The EOM reset switch 24 is also associated with a visual indicator such as a lamp and an audible tone generator that are adapted to be energized when a facsimile transmission is terminated. It will soon be seen that activation of EOM reset switch 24 serves to extinguish the associated energized visual indicator. A CLEAR switch 26, similar to START switch 23, is provided for resetting each of the receive station selecting switches 28-38 upon the manual operation of the CLEAR switch. The CLEAR switch 26 is also provided with a suitable visual indicator, such as a lamp, that may be selectively energized upon the closing of the CLEAR switch 26.

Transmit station selecting means 39 is adapted to select the local facsimile transceiver 2 or any one of the remote facsimile transceivers 3-12 to transmit facsimile information. Accordingly, the transmit station selecting means 39 may be provided with an individual switch associated with each of the facsimile transceivers 2-12 similar to switches 28-38. For a purpose soon to be described, the transmit station selecting means 39 is comprised of a multi-deck rotary switch having a plurality of contacts corresponding to the facsimile transceivers. The positioning of the transmit station selecting means 39 at any one of its plurality of contacts serves to extend a facsimile transmission channel to the associated facsimile transceiver. The transmitstation selecting means 39 is provided with an additional contact identified as ALT to enable the capacity of the station selecting means 1 to be increased as will soon be described. Each contact of the transmit station selecting means 39 that corresponds to a facsimile transceiver is associated with a suitable visual indicator, such as a lamp, adapted to be energized in accordance with the positioning of the transmit station selecting means 39. It will soon become readily apparent that although the transmit station selecting means 39 is illustrated as being comprised of a rotary switch, the transmit station selecting means may include a plurality of push button or toggle switches similar to the switches 28-38.

The front panel of station selecting means 1 illustrated in FIG. 1 includes In Use indicating means 40. The In Use indicating means may comprise a suitable visual indicator such as a lamp that is adapted to be energized when one of the illustrated facsimile transceivers 2-12 is transmitting facsimile information.

Prior to a descriptionof the electrical circuitry that comprises station selecting means 1, the manual operation by an operator of the station selecting means will now be described. The apparatus that is responsive to the manual operation of the station selecting means 1 will be described in detail hereinbelow. The following description of the apparatus illustrated in FIG. 1 will, however, enable one of ordinary skill in the art to appreciate the advantageous features characterizing the instant invention. For purposes of description only, switches 23, 24, 25, 26 and 28-38 are assumed to comprise push button switches. In addition, the visual indicators associated with each of said switches is assumed to comprise a lamp included in the structure of said switch. It is seen therefore, that each of the aforementioned switches are conventional and well known to those of ordinary skill in the art. Nevertheless, it is manifest that the present invention is not limited to the particular structure of the described switches and lamps therefore.

An operator desiring to establish facsimile transmission channels between plural facsimile transceivers initially depresses the POWER ON switch 25 to extend operating energy to the electrical apparatus comprising station selecting means 1. A Power On" lamp associated with POWER ON switch 25 will be energized'to provide a visual indication that operating energy has been extended to the electrical apparatus. Any one of the local or remote facsimile transceivers 2-12 may be selected to transmit facsimile information by appropriately positioning the transmit station selecting means 39. The positioning of transmit station selecting means 39 to one of its contacts establishes a transmission channel between the facsimile transceiver associated with that contact and station selecting means 1. As seen from FIG. 1, the local facsimile transceiver 2 may be selected by an operator to transmit facsimile informationto one or more facsimile transceivers by positioning the transmit station selecting means 39 to station M." In addition, the selecting of a particular facsimile transceiver to transmit facsimile information results in the illumination of an associated transmit lamp. For purposes of explanation, it is assumed that the transmit lamps associated with facsimile transceiver stations 1-10 and M are the same lamps included in the structure of receive station selecting switches 28-38. Alternatively, an individual bank of lamps may be provided to indicate which of the facsimile transceivers has been selected to transmit. Accordingly, in the illustrated embodiment, the selection of local facsimile transceiver 2 to transmit facsimile information results in the constant illumination of the lamp associated with switch 38.

At this time, the receiving capability of the remaining facsimile transceivers coupled to the leased telephone lines, i.e., facsimile transceivers 3-10, is indicated. Let it be assumed that each of the facsimile transceivers 3-10 is comprised of a Telecopier II or Telecopier Ill facsimile transceiver manufactured by Xerox Corporation. Such facsimile transceivers are capable of transmitting status signals representing that the facsimile transceiver is capable of receiving data. These status signals are transmitted regardless of whether the remote facsimile transceiver exhibits an attneded or unattended mode of operation. Failure of the facsimile transceiver to transmit a status signal denotes that said facsimile transceiver is not capable of receiving facsimile information because of a lack of paper, the facsimile transceiver does not admit of its receive mode of operation, in improper coupling to the telephone line, or the like. If facsimile transceivers l1 and 12 are assumed to comprise facsimile transceivers capable of acoustic coupling, such as the Telecopier II or Telecopier III, an analogous status signal is transmitted thereby upon establishing a suitable acoustic connection. Accordingly, those facsimile transceivers 3-12 capable of receiving facsimile information will transmit status signals to station selecting means 1 whereas those facsimile transceivers not capable of receiving facsimile information will not transmit status signals.

The receipt of a status signal is indicated by the extinguishing of an associated one of the lamps included in the switches 28-37. Conversely, the absence of a status signal is indicated by the flashing of an associated one of the lamps included in switches 28-37. For example, if it is assumed that only facsimile transceivers 3, 5, 7, 8, 10, 11 and 12 are capable of receiving facsimile information,then the lamps included in switches 28, 30, 32, 33, 35, 36 and 37 will be extinguished and the lamps associated with switches 29, 31 and 34 will be flashing. Consequently, an operator may now complete a communication channel between the selected local facsimile transceiver 2 and any one or more of the remote facsimile transceivers 3, 5, 7, 8, 10, 11 and 12. An operator should exercise caution in not selecting remote facsimile transceivers 4, 6 or 9 to receive facsimile information since these facsimile transceivers are not capable at this time of receiving such information.

Desired ones of remote facsimile transceivers 3-12 may now be selected to receive facsimile information by depressing those switches 28-37 having extinguished lamps. The selecting of a facsimile transceiver capable of receiving facsimile information is indicated by the illumination of an associated'lamp. Accordingly, if switch means 28, 35 and 36, for example, are depressed, the lamps associated with switches 28, 35, and 36 will now be illuminated. It is understood that the remaining lamps will be extinguished if they are associated with facsimile receivers capable of receiving facsimile information but not selected to receive or will be flashing if they are associated with facsimile transceivers not capable of receiving. The depressing of switches 28, 35 and 36 establishes a communication channel from the local facsimile transceiver 2 selected to transmit to each of the remote facsimile transceivers 3, 10

lected to transmit will not affect the established communication channel. Hence, if switch 38 is now depressed, the selection of local facsimile transceiver 2 to transmit facsimile information will not be altered.

To initiate facsimile transmission between the selected local facsimile transceiver 2 and those selected remote facsimile transceivers, an operator need merely depress START switch 23. The depressing of START switch 23 will cause the lamp associated therewith to be illuminated and, in addition, will extend an enable signal to the facsimile transceiver selected to transmit. Upon receipt of the enable signal, the facsimile transceiver 2 will commence facsimile information transmission. During facsimile information transmission the In Use lamp 40 will be illuminated to apprise the operator that facsimile transmission is taking place. Accordingly, the operator should refrain from further operation of station selecting means 1. Although additional and 11 selected to receive. If an operator erroneously depresses a receive station selecting switch associated with a facsimile transceiver not capable of receiving facsimile information, a communication channel is not extended thereto. in addition, the lamp associated with that erroneously depressed switch continues to flash and an alarm indicator is activated to apprise the operator of his erroneous selection. The alarm indicator may comprise an audio alarm, a visual alarm, or both. In a preferred embodiment of the present invention, the alarm indicator comprises an audio alarm such as a continuous audible tone. The audio alarm may be extinguished by deactivating the erroneously depressed receive station selecting switch. Accordingly, if switches 28-38 are comprised of the well-known push button switches wherein a first depression energizes the switch and a second depression de-energizes the switch, the audio alarm may be extingushed by again depressing. the erroneously depressed switch means. Alternatively, the audio alarm may be extinguished by depressing the CLEAR switch 26. However, the CLEAR switch 26 is adapted to reset all receive station selecting switches to their respective initial quiescent conditions. Accordingly, the completed communication channels that were established by depressing desired ones of the switches 28-37 will be interrupted upon depressing the CLEAR switch 26. In addition, those lamps that were provided with a constant illumination indicating that a communication channel was extended to a facsimile transceiver to enable said facsimile transceiver to receive information will be extinguished by depressing CLEAR switch 26. Accordingly, if an audio alarm is sounded to indicate that a facsimile transceiver has been erroneouslyselected to receive facsimile information, the extinguishing of that audio alarm by depressing the CLEAR switch 26 will require an operator to perform the receive station selecting process once again. Itis here noted that the depressing of CLEAR switch 26 will not interrupt the communica tion channel extended to that facsimile transceiver selected to transmit. Accordingly, the illuminated lamp associated with switch 38, indicating that local facsimile transceiver 2 has been selected to transmit, will not be extinguished. It sill soon be described that the depressing of a receive station selecting switch associated with a facsimile transceiver that has previously been sefacsimile transceivers may be selected to receive during the transmission of facsimile informatiomthe additionally selected facsimile transceivers will not be able to effectively utilize the facsimile information transmitted thereto. It is, of course, appreciated that if the position of transmit station selecting means 39 is now altered or if CLEAR switch 26 is depressed, facsimile transmission will be interrupted.

Upon completion of a facsimile message, facsimile transmission will terminate and the In Use" lamp 40 will be extinguished. In addition, an End of Message lamp will be illuminated and an audio tone is generated to apprise the operator of the termination of facsimile transmission. The audiotone may be a pulsating tone distinct from the aforedescribed audio alarm. For purposes of explantion, the End of Message lamp is included in the structure of EOM reset switch 24. The End of Message lamp may be extinguished by depressing theEOM switch 24. At a predetermined time following the termination of a facsimile transmission, the communication channels extended to those facsimile transceivers that have previously been selected to receive will be interrupted. Furthermore, the illuminated lamps associated with those facsimile transceivers selected to receive will be extinguished and a Clear lamp associated with CLEAR switch 26 will be illuminated. Hence, the station selecting means 1 is returned to its initial or quiescent condition. It may be observed that during the interval of time between the termination of a facsimile transmission and the resetdiately subsequent to the termination of a facsimile transmission by depressing the CLEAR switch 26. Moreover, if it is determined that continuous facsimile transmissions are to obtain between predetermined stations, the communication channels extended to the facsimile transceivers disposed at those stations may be maintained in uninterrupted fashion.

The mode of operation wherein a remote facsimile transceiver is selected to transmit will now be described. After depressing the POWER ON switch 25, an operator may select an appropriate'one of the remote facsimile transceivers 3-12 to transmit merely by positioning the transmit station selecting means 39 to an appropriate location. For example, if remote facsimile transceiver 8 is to transmit facsimile information, the transmit station selecting means 39 is set to position 6. Accordingly, a' communication channel is extended to remote facsimile transceiver 8 via telephone lines 18 and the lamp associated with switch 33 is illuminated. The lamps associated with the remaining switches 28-32 and 34-38 will apprise the operator of the capability of each of the remaining facsimile transceivers to receive the facsimile information. It is recalled that if a facsimile transceiver is not capable of receiving facsimile information a status signal will not be transmitted thereby and the lamp included in the structure of the switch associated therewith will be flashing. However, those facsimile transceivers that are capable of receiving facsimile information will transmit status signals and the lamps included in the switches associated therewith will be extinguished. lf local facsimile transceiver 2 and remote facsimile transceivers 3, 4 and are capable of receiving facsimile information, then the lamps associated with switches 38, 28, 29 and 30, respectively, will be extinguished. The depressing of one or more of the switches 38, 28, 29 and 30 will extend communication channels to the associated facsimile transceivers 2, 3, 4 and 5. In addition, the lamps associated with switches 38, 28, 29 and 30 will now be illuminated. If a switch associated with a lamp that is flashing is erroneously depressed, an audio alarm will sound and a communication channel will not be extended to the associated facsimile transceiver. The communication channels extended to the facsimile transceivers properly selected to receive will not be affected thereby. The audio alarm may be extinguished by again depressing the erroneously depressed receive station selecting switch or by depressing CLEAR switch 26. If switch 33, associated with the remote facsimile transceiver 8 that has previously been selected to transmit, is depressed, the established communication channel to facsimile transceiver 8 is not disturbed but facsimile information will not be transmitted thereby. If, however, the position of transmit station selecting means 39 is altered, the communication channel extended to the remote facsimile transceiver 8 will be interrupted and the lamp associated with switch 33 will be extinguished. If the remote facsimile transceiver 8 is capable of receiving facsimile information, then the lamp associated with switch 33 will remain extinguished. However, if the remote facsimile transceiver 8 is not capable of receiving facsimile information, it is appreciated that the lamp associated with switch 33 will be flashing. The integrity of the communication channels extended to the facsimile transceivers that have been properly selected to receive is dependent upon the ultimate positioning of the transmit station selecting means 39. For example, if the transmit station selecting means 39 is now set to position M, the previously established communication channel to the local facsimile transceiver 2 will be interrupted and a subsequent communication channel will be extended thereto. If, however, the local facsimile transceiver 2 does not admit of its transmit mode, then facsimile transmission will not ensue. A similar result obtains if the transmit station selecting means 39 is set to position 1. It should be noted however that once the transmit station selecting means 39 is rotated from position transceivers selected to receive, the depressing of START switch 23 will initiate facsimile transmission. The subsequent operation of station selecting means 1 is similar to that previously described. Accordingly, in the interest of brevity further description thereof is not here provided.

It is observed that transmit station selecting means 39 is provided with an additional position ALT. The ALT" position enables a plurality of station selecting means tobe combined, thereby increasing the system capacity. In the embodiment illustrated in FIG. 1 a station selecting means 1 is adapted to communicate with ten remote facsimile transceivers. It should be clearly understood that the number of remote facsimile transceivers with which station selecting means 1 may communicate is purely arbitrary and is not intended to provide a limitation for the present invention. However, if it is assumed that a single station selecting means may communicate with 10 remote facsimile transceivers, then two station selecting means may communicate with 20 remote facsimile transceivers, and so on. The combination of a plurality of station selecting means enables any one of the facsimile transceivers coupled thereto to be selected to transmit and any one or more of the remaining facsimile transceivers to be selected to receive notwithstanding the particular station selecting means to which the facsimile transceivers are coupled. For example, if local facsimile transceiver 2 is to transmit facsimile information to remote facsimile transceiver 10 then transmit station selecting means 39 is set to position .M and receive station selecting switch 35 is depressed. If remotefacsimile transceiver 8 is to transmit facsimile information to local facsimile transceiver 2 and to remote facsimile transceiver 3 then transmit station selecting means 39 is set to position 6 and receive station selecting switch means 38 and 28 are depressed. If now, remote facsimile transceiver 4 is to transmit facsimile information to a facsimile transceiver associated with another station selecting means, then transmit station selecting means 39 is set to position 2 and the appropriate receive station selecting switch of the other station selecting means is depressed. Further, if a facsimile transceiver associated with the other station selecting means is to transmit facsimile information to remote facsimile transceivers 5 and 7, then transmit station selecting means 39 is set to position ALT and receive station selecting switches 30 and 32 are depressed. Finally, if none of facsimile transceivers 2-12 is to transmit or receive facsimile information then transmit station selecting means 39 is set to position ALT and none of the received station selecting means is depressed.

It is noted that, since station selecting means 1 and remote facsimile transceivers 312 may be coupled to leased telephone lines by the coupling means described in aforementioned US. Pat. application Ser. No. (P/2176), the instant invention admits of an unattended mode of operation as described in detail in said application.

The electrical apparatus comprising the station selecting means 1 and the manner in which said appara- 203, receive station selecting means 204 and control means 205. Data signal transmit means 201 is adapted to receive facsimile information transmitted thereto from a facsimile transceiver selected to transmit and to retransmit said facsimile information to those facsimile transceivers selected to receive. The data signal transmit means 201 includes wave shaping means for shaping the transmitted facsimile information signal in a manner such that the signals are compatible with the communication medium extended to each of the facsimile transceivers. It is recalled that the remote facsimile transceivers, illustrated herein as facsimile transceivers 213a 213j, are coupled to conventional telephone lines 220a 220 The data signal transmit means 201 is interconnected between transmit station selecting means 203 and receive station selecting means 204.

Data signal receive means 202 is adapted to supply data signal transmit means 201 with facsimile information signals transmitted thereto over telephone lines 220a 220j. In addition, data signal receive means 202 is capable of supplying control means 205 with signals representing the status of remote facsimile transceivers 213a 213j. Accordingly, data signal receive means 202 includes a plurality of input terminals coupled to associated ones of remote facsimile transceivers 213a 213j via telephone lines 2200 2201'. The output terminals of data signal receive means 202 are coupled to transmit station selecting means 203. The transmit station selecting means 203 serves to couple the facsimile information data signals received from a facsimile transceiver selected to transmit to data signal transmit means 201. Accordingly, transmit station selecting means 203 corresponds to transmit station selecting means 39 previously described with reference to FIG. 1 and may comprise a multi-deck rotary switch means having a plurality of stationary contacts and a movable contact. Each stationary contact may be coupled to a respective output terminal of data signal receive means 202. An additional stationary contact may be coupled to the local facsimile transceiver 212 and is adapted to receive facsimile information signals therefrom. The movable contact is coupled to data signal transmit means 201. Accordingly, a selected one of the output terminals of data signal receive means 202 may be connected to the input terminal of data signal transmit means 201' in accordance with the positioning of the movablecontact of transmit station selecting means 203. In addition, the movable contact admits of a predetermined position wherein the local facsimile transceiver 212 is coupled to the input terminal of data signal transmit means 201. It will soon be seen that, if desired, transmit station selecting means 203 may comprise a bank of individually operated switch means, each admitting of an open and closed position. It is understood that the function performed by a bank of individually operated switch means is identical to the function performed by a rotary switch means. Other equivalent embodiments of transmit station selecting means 203 will become obvious to those skilled in the art.

Receive station selecting means 204 is coupled to data signal transmit means 201 and is adapted to establish a communication channel between data signal transmit means 201 and those facsimile transceivers selected to receive. The receive station selecting means 204 may comprise a plurality of activatable switching means corresponding in number to the remote facsimile transceiver 213a 213j. The activatable switching means are operated under the control of control means 205 and serve to complete a connection betweenthe output terminal of data signal transmit means 201 and selected ones of telephone lines 2200 220 to which the remote facsimile transceivers 213a 2l3j are coupled.

Control means 205 is coupled to receive station selecting means 204 and is adapted to assure that a facsimile transceiver capable of receiving data is properly selected. Accordingly, the control means 205 is capable of supplying activating signals to receive station selecting means 204 whereby the activatable switching means included therein are operated. The control signals supplied to receive station selecting means 204 are derived from signals generated by the manual operation of switching devices such as the switching means illustrated in FIG. 1. The aforementioned status signals received from the remote facsimile transceivers 213a 2l3j by data signal receive means 202, together with analogous status signals generated by the local facsimile transceiver 212, are supplied to control means 205 whereat they are utilized in generating suitable control signals. Control means 205 is also responsive to transmit station selecting means 203 to extend a transmission enable signal to that facsimile transceiver selected by transmit station selecting means 203 to transmit. Furthermore, error signals are produced by control means 205 to indicate an erroneous manual operation performed by an operator. Finally the control means 205 is adapted to. control the transmission of facsimile information to and from the local facsimile transceiver 212. The control means 205 is described in more detail hereinbelow with respect to FIGS. 3 and 4 and is comprised of the logic circuits illustrated in FIGS. 6, 7 and 8.

.Theoperation of the apparatus illustrated in FIG. 2 will now be described. The control means 205 will be described only to the extent necessary to facilitate an understanding of the operation of the apparatus illustrated in FIG. 2. A complete description of the control means 205 is set forth hereinbelow with reference to the block diagrams of FIGS. 3 and 4 and the logic circuits of FIGS. 6, 7 and 8. It is clear that the electrical apparatus of FIG. 2 comprises the substance of the station selecting means previously described with reference to FIG. 1 and therefore is operable in response to an operator initiated action. Accordingly, the electrical apparatus is supplied with operating energy derived At this time, status signals representing the capability of the remote facsimile transceivers 213a 213j are selectively transmitted thereby and received by data signal receive means 202 over telephone lines 220a 220j. It is seen that the data signal receive means 202 is directly coupled to the telephone lines 220a 220j and therefore, the receipt of the status signals is not dependent upon the operation of receive station selecting means 204. If a status signal is received, data signal receive means 202 identifies the particular remote facsimile transceiver 213a 213j from which the status signal originates and supplies control means 205 with a manifestation of the detected status signal. The status signal may be a particular d.c. level, a pulse coded signal, an ac. signal admitting of a predetermined frequency, or the like. In a preferred embodiment of the present invention the status signal is an ac. signal admitting of a predetermined frequency. Accordingly, data signal receive means 202 may include a plurality of suitable tone detectors coupled to corresponding ones of telephone lines 220a 220j.

Control means 205 includes suitable circuitry, soon to be described in detail, that is responsive to the detection of the status signals by data signal receive means 202 to provide visual indications of the status of the remote facsimile transceivers 213a 213]. Hence, control means 205 is coupled to each of the tone detectors included in data signal receive means 202 and, in addition, includes a plurality of lamps corresponding to the remote facsimile transceiver 213a 213j. It is appreciated, therefore, that the lamps included in control means 205 may be identical to the lamps previously described with respect to switches 2837 of FIG. 1. Thus, it is seen that if facsimile transceiver 213a, for example, is capable of receiving facsimile information, a status signal will be transmitted thereby over telephone line 2200 and received by an associated one of the tone detectors included in data signal receive means 202. The tone detector to which the status signal is supplied supplies control means 205 with a representative signal whereupon the lamp included in control means 205 and associated with the facsimile transceiver 213a is extinguished. If facsimile transceiver 213b, for example, is not capable of receiving facsimile information, a status signal will not be generated thereby. Accordingly, the tone detector included in data signal receive means 202 and associated with the facsimile transceiver 213b will not receive a status signal from the telephone line 22012 coupled thereto. Hence, the tone detector associated with facsimile transceiver 2l3b will not supply control means 205 with a signal representative of the detection of a status signal. Consequently, the lamp included in control means 205 and associated with the facsimile transceiver 213b will not be extinguished but will be flashing. In a manner identical to that just described, data signal receive means 202 will receive status signals from those remote facsimile transceivers 213a 2l3j capable of receiving facsimile information, and will apprise control means 205 thereof. Control means 205 will, in turn, produce visual indications representing the status of each of the remote facsimile transceivers 213a 213].

Local facsimile transceiver 212 is directly coupled to control means 205 and, therefore, may directly apprise the control means 205 of the capability thereof to receive facsimile information. Hence, an analogous status signal is transmitted from the local facsimile transceiver 212 to control means 205 whereat a visual indication of the status of the local facsimile transceiver 212 is produced. This visual indication may be provided by the selective illumination of a lamp similar to the lamp associated with switch 38 previously described with reference to FIG. 1. It will be seen from the forthcoming description that the analogous status signal transmitted by facsimile transceiver 212 represents that the local facsimile transceiver is in its receive mode and is provided with a suitable supply of paper upon which received facsimile information is recorded. The analogous status signal may be a do. level, a pulse coded signal, or an a.c. signal admitting of a predetermined frequency. In the preferred embodiment of the present invention, the analogous status signal is comprised of a logic signal which may be a dc. level.

The control means 205 is now prepared for the manual operation whereby one or more facsimile transceivers are selected to receive facsimile information. Such manual operation may be effected by the closing of switches such as the selective depressing of switches 28-38 illustrated in FIG. 1. The manual operation of the switches produces select signals that are combined with the detected response of the data signal receive means 202 to received status signals to supply receive station selecting means 204 with selective activating signals. Thus, an activating signal associated with a remote facsimile transceiver will be generated if data signal receive means 202 receives a status signal from said remote facsimile transceiver and a switch associated with that remote facsimile transceiver is manually operated. In accordance with the previously assumed example, a status signal is detected by data signal receive means 202 from remote facsimile transceiver 213a. If the switch associated with the remote facsimile transceiver 2130, such as switch 28 of FIG. 1, is manually operated, the select signal generated thereby is combined with the signals supplied to the control means 205 by data signal receive means 202 representative of the detection of a status signal. Consequently, an activating signal is supplied to receive station selecting means 204 by control means 205. Should a switch associated with a remote facsimile transceiver not capable of receiving facsimile information be erroneously operated, e.g., should a switch associated with a flashing lamp be depressed, control means 205 provides an indication of erroneous operation and an activating signal will not be supplied to receive station selecting means 204. Thus, if a switch associated with remote facsimile transceiver 213b, such as the switch 29 illustrated in FIG. 1, is manually operated, a select signal will be produced by control means 205. However, data signal receive means 202 has not detected a status signal received from the remote facsimile transceiver 213!) and, therefore, the data signal receive means 202 will not supply control means 205 with a signal representative of the detection of a status signal. Consequently, the select signal produced by the manual operation of the switch, such as switch 29, is not combined with a representative signal. Hence, a resulting activating signal is not generated. The control means 205 includes further circuitry to detect the presence of a select signal and the absence of a signal representative of the detection of a status signal to produce an audio alarm signal. The audio alarm signal is supplied to a suitable alarm tone generator similar to that described with reference to FIG. 1 to thereby indicate an erroneous manual operation. it will become clear from the forthcoming description of control means 205 that the control means includes individual circuits associated with each of the facsimile transceivers such that the erroneous manual operation of one switch has no debilitating effect upon the correct manual operation of another switch.

A select signal is produced upon the manual operation of the switch associated with the local facsimile transceiver 212, such as switch 38 of FIG. 1. This select signal is combined with the analogous status signal generated by'the local facsimile transceiver 212 to produce a further activating signal. The further activating signal is supplied directly by the control means 205 to the local facsimile transceiver 212 to enable the local facsimile transceiver to receive facsimile information subsequently transmitted. An erroneous manual operation of the switch associated with the local facsimile transceiver 212, i.e., a depressing of switch 38 of FIG. 1, results in theproduction of a select signal in the absence of an analogous status signal. Accordingly, control means 205 produces an audio alarm signal similar to that produced upon the erroneous manual operation of a switch such as-switches 28-37, described hereinabove.

The activatable switch means included in receive station selecting means 204 areresponsive to the activating signal supplied thereto by control means 205. Accordingly, if an activating signal is supplied to receive station selecting means 204 by control means 205 in response to the manual operation of the switch associated with facsimile transceiver 213a, then an activatable'switch means isclosed to provide an electrical connection between data signal transmit means 201 and the telephone line 220a. It is seen therefore, that the activatable switch means included in receive station selecting means 204 are effective to establish communication channels between data signal transmit means 201 and selected ones of the remote facsimile transceivers 213a 2l3j under the control of control means 205. lt will be seen from the more detailed description set forth hereinbelow that a fixed communication channel is provided between data signal transmit means 201and local facsimile transceiver 212 to enable the local facsimile transceiver to receive transmitted facsimile information. However, the operation of the local facsimile transceiver 212 in response to the received facsimile information is strictly regulated in accordance with the signal produced by control means 205.

It is here noted that control means 205 includes additional circuitry, described in detail below, for inhibiting the simultaneous selection of a given facsimile transceiver to both transmit and receive facsimile information. The manual operation of transmit station selecting means 203 produces a signal identifying the particular facsimile transceiver selected to transmit. This signal is of a manually operated switch has been described in detail with respect to the operation of receive station selecting switches 28-38 of FIG. 1 and need not be further described herein. The Clear signal is generated by control means 205 in response to the manual operation of a clear switch such as CLEAR switch 26 of FIG. 1. It is now appreciated that if the erroneously produced select signal is'terminated by the manual operation of the CLEAR switch, the aforedescribed process of selecting one or more facsimile transceivers to receive facsimile information must be repeated.

The apparatus illustrated in FIG. 2 is adapted for facsimile transmission upon the appropriate positioning of transmit station selecting means 203 and the activation of receive station selecting means 204. The input terminal of data transmit means 201 is thus connected to one of the stationary contacts included in transmit station selecting means 203 through the moveable contact thereof, and the output terminal of data signal transmit means 201 is connected to one or more of the telephone lines 220a 220j. Continuous communication channels are thereby established from data signal receive means 202 through transmit station selecting means 203 to data signal transmit means 201, and from data signal transmit means 201 through receive station selecting means 204 to. selected ones of the telephone lines 220a 220j. It is recognized that if local facsimile transceiver 212 is selected to transmit facsimile information, then continous communication channels are established between the local facsimile transceiver 212 through transmit station selecting means 203 to data signal transmit means 201, and from data signal transmit means 201 through receive station selecting means 204 to selected ones of the telephone lines 220a 220j. Facsimile transmission is initiated by a manual operation that causes control means 205 to generate an enabling signal. The generated enabling signal is applied by control means 205 to that telephone line 220a 220j associated with the stationary contact at which the movable contact of transmit station selectingmeans 203 is positioned. It will be seen from the description offered hereinbelow that if the movable contact of transmit station selecting means 203 is positioned at the stationary contact to which the local facsimile transceiver 212 is connected, the enabling signal generated by control means 205 is applied directly to the local facsimile transceiver 212. Thus, the applied enabling signal is transmitted to that facsimile transceiver selected by transmit station selecting means 203 to transmit facsimile information. It is recognized that a facsimile transceiver similar to the aforementioned Telecopier H or Telecopier Ill facsimile transceiver automatically responds to the received enabling signal to commence transmission of facsimileinformation. Facsimile information is transmitted by the facsimile transceiver selected to transmit, via the telephone line coupled thereto to data signal receive means 202. The waveform of the facsimile information signal received by data signal receive means 202 is appropriately shaped and is coupled to data signal transmit means 201 by transmit station selecting means 203. Data signal transmit means 201 further shapes the waveform of the facsimile information signal in a manner that is compatible for transmission over selected ones of the telephone lines 2200 220j. Receive station selecting means 204 receives the further shaped facsimile information signal and applies such facsimile information is transmitted over the telephone lines to the remotefacsimile transceivers that have been-selected by receive station selecting means 204 in cooperation with control means 205 to receive. It should be readily apparent that if the local facsimile transceiver 212 has been properly selected to receive facsimile information, the further shaped facsimile information signal provided by data signal transmit means 201 is applied therefrom to the local facsimile transceiver. Similarly, if the local facsimile transceiver 212 is selected to transmit, a facsimile information signal is supplied by the local facsimile transceiver to transmit station selecting means 203 which, in turn, applies the facsimile information signal todata signal transmit means 201.

The completion of a facsimile transmission is detected by control means 205 which provides an indication thereof. Suitable circuitry, such as a time delay circuit, responds to said indication to produce a Clear signal at a predetermined time subsequent to the completion of a facsimile transmission.

It is recalled that the Clear signal is effective to ter- 'minate each select signal produced by control means 205, thereby deactivating each of the previously activated switches included in receive station selecting means 204. Accordingly, data signal transmit means 201 is disconnected from each of the telephone lines 220a 220]. The Clear signal is further effective to terminate the signal supplied to the local facsimile transceiver 212 by control means 205 whereby the local facsimile transceiver is no longer operable on received facsimile information signals. Should a subsequent facsimile transmission ensue prior to the generation of the Clear signal, control means 205 will generate the Clear signal only after completion of the subsequent facsimile transmission. However, the Clear signal may be generated at any time in accordance with the manual operation of a clear switch such as by depressing the CLEAR switch 26 illustrated in FIG. 1. The deactivation of receive station selecting means 204 returns the illustrated apparatus to its initial or quiescent condition whereby the apparatus is prepared to establish further communication channels between plural facsimile transceivers in the aforedescribed manner.

Although the foregoing has described manual operation initiated by an operator, the inherent nature of the leased line coupling device that may be utilized with the present invention, as disclosed in copending application Ser. No. 165,455, enables an unattended mode of operation wherein facsimile information may be automatically transmitted and received in response to a remote request.

In light of the foregoing description, it is manifest that control means 205 controls the operation of receive station selecting means 204 and the operation of the local facsimile transceiver 212. Control means 205 also functions to initiate a facsimile transmission and to detect the completion thereof. A block diagram of the means 301, enable selected receive means 302 and indicating means 303. Status detecting means 301 is adapted to monitor the capability of each of the remote facsimile transceivers to receive facsimile information. Status detecting means 301 is thus supplied with signals representing that status signals have been received from the-remote facsimile transceivers. Status detecting means 301 is further supplied with select signals produced by the manual operation of switches such as the receive station selecting switches illustrated in FIG. 1. In addition, status detecting means 301 is provided with a signal identifying the remote facsimile transceiver that has been selected to transmit. A first output terminal of status detecting means 301 is coupled to enable selected receive means 302 and a second output terminal of status detecting means 301 is coupled to indicating means 303.

Enable selected receive means 302 is adapted to enable a' communication channel to be extended to those remote facsimile transceivers selected to receive in accordance with the signals supplied thereto by status detecting means 301. Accordingly, enable selected receive means 302 may comprise a plurality of activating means each being associated with a corresponding one of the switch means included in receive station selecting means 204. A signal supplied to one of the activat ing means of enable selected receive means 302 by status detecting means 301 results in the activation of the corresponding one of the switch means of receive station selecting means 204.

' Indicating means 303 may comprise a plurality of visual indicating means each being associated with a corresponding one of the remote facsimile transceivers. The indicating means 303 are selectively energized by signals supplied thereto by status detecting means 301 to provide visual indications of the status of each of the remote facsimile transceivers. The indicating means 303 may therefore comprise a plurality of lamps such as the lamps associated with receive station selecting switches 28-37 of FIG. 1. Briefly, each of the indicating means 303 serves to provide a first indication when an associated remote facsimile transceiver is not capable of receiving facsimile information, a second indication when the associated facsimile transceiver is capable of receiving facsimile information and a third indication when the associated facsimile transceiver has been properly selectedto receive or transmit facsimile information. It is recalled that the first indication may be provided by a flashing lamp, the second indication may be provided by an extinguished lamp and the third indication may be provided by a lamp admitting of constant illumination.

A complete description of the block diagram illustrated in FIG. 3 is provided hereinbelow with reference to the logic circuit illustrated in FIG. 6. Nevertheless, a brief analysis of the operation of the block diagram is provided to facilitate a ready understanding of the instant invention. Status detecting means 301 is responsiveto a status signal received from a remote facsimile transceiver to supply indicating means 303 with an appropriate signal to extinguish the lamp associated with that remote facsimile transceiver. It is recalled that a status signal represents that the remote facsimile transceiver is capable of receiving facsimile information.

Thus, status detecting means 301 is coupled to the data signal receive means 202 previously described with reference to FIG. 2. More particularly, the status detecting means 301 may include a plurality of input terminals each coupled to a corresponding one of the tone means 202. It should be appreciated that if status detecting means 301 is not provided with a signal from one of the tone detecting means, a corresponding one of the indicating means 303 is not supplied with an extinguishing signal and said corresponding one of the indicatingmeans 303 exhibits a pulsating illumination.

Each of the select signals generated by the manual operation of the receive station selecting switches illustrated in FIG. 1 is supplied to status detecting means 301. Status detecting means 301 compares each select signal with a corresponding status signal. If a remote facsimile transceiver that is capable of receiving facsimile information is selected to receive then status detecting means 301will be supplied with a select signal and a status signal for that facsimile transceiver. Accordingly, enable selected receiver means 302 will be provided with an activating signal to enable a communication channel to be extended to that remote facsimile transceiver. In addition, a corresponding one of the indicating means 303 will be provided with a suitable signal such that the indicating means exhibits a constant illumination. However, if a remote facsimile transceiver that is not capable of receiving facsimile information is selected to receive, then status detecting means 301 will be supplied with a select signal but not with a status signal. Hence, an activating signal is not transmitted to enable selected receive means 302 and a communication channel is not extended to that remote facsimile transceiver. Moreover, the combination of a produced select signal and the. absence of a status signal is indicative of an erroneous selection of a remote facsimile transceiver. Accordingly, a corresponding one of the indicating means 303 is not supplied with an extinguishing signal to extinguish the pulsating illumination thereof. Status detecting means 301 includes further means that responds to a select signal associated with a remote facsimile transceiver that is not capable of receiving facsimile information to' generate an audio alarm signal. It is now recognized that the audio alarm signal serves to apprise an operator of an erroneous manual operation.

The signal. that identifies the particular remote facsimile transceiver that has been selected to transmit facsimile, information is utilized by status detecting means 301 to prevent an erroneous selection of that same facsimile transceiver to receive. Thus, an activating signal is not supplied to enable selected receive means'302 by status detecting means 301 if a select signal, a status signal and an identifying signal, all associated with the same remote facsimile transceiver, are applied to status detecting means 301. Nevertheless, application to status detecting means 301 of the signal identifying the particularre'mote facsimile transceiver that has been'selected to transmit is effective to supply a corresponding one of the indicating means 303 with an illuminating signal. Consequently, one of the indicating means 303 will exhibit a constant illumination indicating that the corresponding remote facsimile transceiver has been selected to transmit facsimile in formation. Upon the completion of a facsimile transmission, eachof the selected signals supplied to status detecting means 301 si' terminated. Hence, status detecting means 301 returns toits initial quiescent condi tion. Accordingly, the activating signals and constant illumination signals supplied to enable selected receive means 302 and indicating means 303, respectively, are terminated.

A block diagram of the portion of control means 205 that serves to regulate the operation of the local facsim ile transceiver, initiate a facsimile transmission and detect the completion of a facsimile transmission is illustrated in FIG. 4 and comprises data detecting means 401, transmit enable means 402, local status detecting means 405 and local facsimile enable means 406. Data detecting means 401 is adapted to detect the transmission of facsimile information to a facsimile transceiver by the data signal transmit means 201 of FIG. 2. A complete description of data detecting means 401 is set forth hereinbelow with reference to FIG. 7. It is sufficient for a ready understanding of the block diagram of FIG. 4 to note that data detecting means 401 is capable of detecting characteristic signals that are transmitted only during a facsimile transmission. Accordingly, data detecting means 401 includes an input terminal coupled to the output of data signal transmit means 201.

An output terminal of data detecting means 401 is coupled to transmit enable means 402 for a purpose soon to be described. Transmit enable means 402 is adapted to generate an enabling signal that is transmitted to the remote facsimile transceiver selected to transmit facsimile information. Accordingly, transmit enable means 402 is comprised of a suitable signal generator such as a pulse signal generator, an a.c. signal generator or the like. In the preferred embodiment of the present invention, the enabling signal is an a.c. signal admitting of a predetermined frequency. Hence, transmit enable means 402 is preferably comprised of an a.c. signal generator. The output terminal of transmit enable means 402 is selectively coupled through suitable switching means to the telephone line to which the remote facsimile transceiver is coupled. The switching means may thus be similar to the transmit station selecting means 203 of FIG. 2 and is adapted for simultaneous operation therewith such that an enabling signal is transmitted to the remote facsimile transceiver that has been selected to transmit facsimile information. It should be clearly recognized by those of ordinary skill in the art that the transmission of an enabling signal to a remote facsimile transceiver that is in the process of transmitting facsimile information will result in the degradation and distortion of the transmitted facsimile information. Accordingly, it is preferred not to transmit the enabling signal during a facsimile transmission. Hence, transmit enable means 402 is provided with a first inhibit input terminal to which data detecting means 401 is coupled.

Data detecting means 401 is additionally coupled to end of message detecting means 403. The end of message detecting means 403 is capable of detecting the completion of a facsimile transmission and for providing a signal indicative thereof. A further description of end of messagedetectingmeans 403 and the manner in which the completion of a facsimile transmission is. detectedis set forth hereinbelow with reference to FIG.

'7. Suffice it to say, however, the termination of the viously described with respect to EOM reset switch 24 illustrated in FIG. 1, together with an audio tone generator.

Local status detecting means 405 is similar to aforedescribed status detecting means 301 and serves to perform an analogous function. Accordingly, local status detecting means 405 is adapted tomonitor the capability of the local facsimile transceiver to receive or transmit facsimile information. Local status detecting means 405 is therefore directly coupled to the local facsimile transceiver and is responsive to analogous status signals representing the capability of the local facsimile transceiver to receive or to transmit facsimile information. Also, local status detecting means 405 is adapted to receive a select signal produced upon the manual operation of a switch such as switch 38 of FIG. 1. Furthermore, a signal identifying that the local facsimile transceiver has been selected to transmit facsimile information is supplied to local status detecting means 405. Hence, local status detecting means 405 may be coupled to an appropriate one of the stationary contacts included in the switch means comprising transmit station selecting means 203.

An output terminal of local status detecting means 405 is coupled to local facsimile enable means 406 which is adapted to regulate the appropriate operation of the local facsimile transceiver in accordance with the manifestations received from local status detecting means 405. Local facsimile enable means 406 will be described in more detail hereinbelow with reference to FIG. 8. Local status detecting means 405 is additionally coupled to indicating means 407. Indicating means 407 may comprise a visual indicating means such as a lamp similar to the lamp associated with receive station selecting switch 38, and is capable of indicating the particular status exhibited by the local facsimile transceiver. In addition, indicating means 407 may include an audio alarm indicator that is activated when the local facsimile transceiver is erroneously selected to receive facsimile information. It will be apparent that indicating means 407 provides a first visual indication,

A second indication, such as an extinguished lamp, is provided when the local facsimile transceiver is capable of receiving information. And a third indication, such as a constant illumination, is provided when the local facsimile transceiver is properly selected to transmit or to receive facsimile information.

In operation, local status detecting means 405 is supplied with signals representing the status of the local facsimile transceiver. For example, if the local facsimile transceiver admits of its receive mode of operation and paper upon which received facsimile information is recorded is suitably supplied, then a signal is applied to local status detecting means 405 representing that tecting means 405 if the local status detecting means is directly coupled to the local facsimile transceiver. It should now be appreciated that a select signal is-applied to local status detecting means 405 upon the manual operation of the appropriate receive station selecting switch. The local status detecting means 405 compares the local facsimile status signals supplied thereto with the produced select signal to determine if the local facsimile transceiver has been properly selected to receive. Hence, if the local facsimile transceiver is capable of receiving facsimile information and the local facsimile transceiver has been selected to receive then local status detecting means 405 responds to the two signals supplied thereto to apply an activating signal to local facsimile enable means 406. Receipt of this activating signal by local facsimile enable means 406 results in a suitable control signal applied to the local facsimile transceiver whereby the local facsimile transceiver is enabled to execute a receive operation. In addition, an illuminating signal is applied to indicating means 407 by local status detecting means 405 whereby a constant illumination is provided indicating that the local facsimile transceiver has been properly selected to receive.

Local status detecting means 405 also receives a signal that is generated when the local facsimile transceiver is selected to transmit. It is recalled that this signal is generated in response to the appropriate manual operation of transmit station selecting means 203 and serves to identify the particular facsimile transceiver selected to transmit. Local status detecting means 405 compares the local facsimile status signals and the generated identifying signal supplied thereto to determine if the local facsimile transceiver has been properly selected to transmit. Accordingly, local status detecting means 405 supplies local facsimile enable means 406 with an appropriate activating signal when the local facsimile transceiver admits of its transmit mode of operation and the local facsimile transceiver has been selected to transmit. Local facsimile enable means 406 responds tothe applied activating signal to supply the local facsimile transceiver with a suitable control signal whereby the local facsimile transceiver is enabled to execute a transmit operation. In addition, local status detecting means 405 supplies indicating means 407 with an illuminating signal to effect the constant illumination of the visual indicating means, thereby indicating that the local facsimile transceiver has been selected to transmit.

It is observed that if a select signal is applied to local status detecting means 405 in the absense of a local facthe local facsimile transceiver is capable of receiving simile status signal representing that the local facsimile transceiver is capable of receiving, local facsimile enable means 406 is not supplied with an activating signal. Moreover, the absence of a suitable local facsimile status signal is sensed and local status detecting means generates an appropriate audio alarm signal to indicate the erroneous selection of the local facsimile transceiver to receive facsimile information. Similarly, if the local facsimile transceiver is not capable of transmitting the local status detecting means 405 will not be supplied with an appropriate status signal. If the local facsimile transceiver is then erroneously selected to transmit, local status detecting means 405 senses the absence of an appropriate local facsimile status signal and does not supply local facsimile enable means 406 with an activating signal. If an operator erroneously selects the local facsimile transceiver to both receive and transmit facsimile information, local status detecting means 405 will supply local facsimile enable means 406 with an activating signal only if the local facsimile transceiver admits of its transmit mode. In addition, the local status detecting means 405 will generate an audio alarm signal to indicate an erroneous manual operation.

' Transmit enable means 402 generates an a.c. signal of a predetermined frequency which signal is applied to the telephone line to which a remote facsimile transceiverthat has been selected to transmit is coupled. Suitable switch means that is operated simultaneously with the manual operation of transmit station selecting means 203 supplies the enabling signal from transmit enable means 402 to the appropriate telephone line. In light of the aforedescribed operation of local facsimile enable means 406, itis clear that the enabling signal generated by transmit enable means 402 need not be applied to the local facsimile transceiver. Accordingly, the operation of transmit enable means 402 is inhibited when the local facsimile transceiver is selected to transmit. Hence, transmit enable means 402 is provided with a second inhibit input terminal to which is supplied the generated signal identifying the local facsimile transceiver as the facsimile transceiver selected to transmit. Alternatively, the switch means coupled to the output terminal of transmit enable means 402 may include 24' tecting means 401 responds to the detected facsimile transmission to supply end of message detecting means 403 with a data detect signal. End of message detecting means 403 is responsive to the termination of a data detect signal to produce suitable indicating signals that are supplied to indicating means 404. Thus, when a facsimile transmission is completed, the data detect signal produced by data detecting means 401 is terminated. Accordingly, end of message detecting means 403 generates an end of message audio signal and an end of message illuminating signal. Indicating means 404 may include a suitable visual indicating means, such as a lamp similar to the lamp described with respect to EOM reset switch 24, that admits of a constant illumination upon the completion of a facsimile transmission. In addition, an audio indicator may be provided to produce a characteristic tone in response to the end of message audio signal. It is appreciated therefore that suitable indications are provided upon the completion of a facsimile transmission. End of message detecting means 403 may be reset to its initial condition upon the manual operation of an appropriate switch means such as EOM reset switch 24. The response of data detecting means 401 to a completed facsimile transmission may contacts coupled only to the telephone lines to which the remote facsimile transceivers are coupled. Consequently, transmit enable means 402 will not be provided with a transmission path from the output terminal thereof to the local facsimile transceiver. Hence, when the local facsimile transceiver is selected to receive the enabling signal generated by transmit enable means 402 willnot be supplied thereto. v

The operation of transmit station selecting means 203 taken with the operation of status detecting means 301' and enable selected receive means 302 as well as local status detecting means 405 and local facsimile enable means 406 establishes communication channels between the facsimile transceiver selected to transmit and the one or more facsimile transceivers selected to receive. Facsimile information may now be transmitted over the established communication channels. It is recalled that facsimile information is transmitted to those facsimile transceivers selected to receive by data signal transmit means 201. In addition, the transmitted facsimile information is coupled from data signal transmit means 201 to data detecting means 401. As has been noted he'reinabove, data detecting means 401 includes suitable circuitry soon to be described, that detects signals that are characteristic of a facsimile transmission.

In a facsimile transmission system, facsimile information is conveyed in the well-known manner by transmitting black, white and gray signals. In a system wherein the present invention may be utilized it is contemplated that a white signal is transmitted only during a facsimile transmission. Accordingly, data detecting means 401 may, for example, include a white signal detector, such .as a filtering device sharply tuned to the frequency of a white signal ora threshold detector responsive to the amplitude of a white signal. I

During a facsimile transmission, data detecting means 401 applies a signal to the first inhibit input terminal -of transmit,enable means 402 to terminate the generation of an enabling signal. In addition, data debe utilized to generate an appropriate Clear" signal that is applied to status detecting means 301 and to local status detecting means 405 to reset the respective status detecting means to their initial conditions. The output terminal of data detecting means 401 may therefore be coupled to a suitable timing means such that the Clear signal is generated at a predetermined time subsequent to the completion of a facsimile transmission. Data detecting means 401 and end of message detecting means 403 will be described in greater detail hereinbelow with reference to FIG. 7.

Data signal transmit means 201, data signal receive means 202, transmit station selecting means 203 and receive station selecting means 204 are shown in more detail in the partial block and the partial schematic diagram of FIG. 5. Data signal transmit means 201 is comprised of amplitude equalizing means 501, filter means 502, phase equalizing means 503 and amplifying means 504. Amplitude equalizing means 501 is adapted to adjust the amplitude of a signal supplied thereto whereby the supplied signal is made compatible with the particu- I lar communication channel to which it is ultimately applied. In the preferred utilization of the present invention, facsimile information is transmitted over telephone lines. The amplitude varying characteristics of a telephone line vary in a non-linear manner with respect to the frequency of a signal transmitted thereover. Accordingly, amplitude equalizing means 501 is adapted to compensate the amplitude of the signal supplied thereto whereby a signal is obtained having an amplitude that is sufficient for transmission over a telephone line. Hence, amplitude equalizing means 501 may comprise a variable gain amplifier having an amplification factor that is complementary with the attenuating characteristics of the telephone lines. It should be understood that the non-linear amplification factor may be greater or less than unity.

wanted frequencies from the signals supplied thereto. It will soon be seen that the signal provided at the input terminal of amplitude equalizing means 501 exhibits a substantially rectangular waveform and therefore is comprised of the odd harmonics of a fundamental sinusoid. The frequency characteristics of a telephone line result in undesirable distortion of the higher harmonics whereby adequate data transmission cannot obtain. Moreover, public telephone operating companies prohibit the transmission of higher harmonics over the facilities thereof. Accordingly, filter means 502 is capable of removing the harmonic frequencies of a fundamental sinusoid such that phase equalizing means 503 is supplied with a signal that exhibits a sinusoidal waveform compatible with the telephone lines. A further undesireable feature of conventional telephone lines is the inherent phase distorting characteristics thereof. The phase distortion of a telephone line varies in a nonlinear manner with respect to the frequency of a signal transmitted thereover. Phase equalizing means 503 is adapted to compensate for the non-linear phase distorting characteristics by adding a compensating nonlinear distortion to the signals supplied thereto by filter means 502. Thus, the signals transmitted over the telephone lines will be subjected to a linear phase shift characteristic irrespective of the frequencies thereof. Deleterious effects attributed to the distortion characteristics of the telephone lines are thereby mitigated. Phase equalizing means 503 may, therefore, comprise a conventional variable phase shift circuit well known in the prior art. Amplifying means 504 is coupled to phase equalizing means 503 at an input terminal thereof and is coupled to receive station selecting means 204 at an output terminal thereof. Amplifying means 504 is adapted to provide a final adjustment in the amplitude of the signal to be tranmitted over the telephone line, Accordingly, if the signal provided at the output terminal of phase equalizing means 503 admits of sufficient amplitude, amplifying means 504 may be omitted.

Receive station selecting means 204 is adapted toselectively supply the signals provided at the output terminal of amplifying means 504 to those telephone lines coupled to remote facsimile transceivers selected to receive. Accordingly, receive station selecting means 204 may comprise a plurality of activatable switch means R'l-R'IO each of which is associated with a corresponding one of the telephone lines. The activatable switch means may comprise conventional relay contact, transistor switch means, or the like. The input terminals of the activatable switch means Rl-Rl are connected in common relation to the output terminal of amplifier means 504. The output terminal of each activatable switch means is ac. coupled to a corresponding telephone line by the circuit comprised of series connected resistance means 505, adapted to limit the amplitude of the signals transmitted over the telephone line in accordance with the requirements of the public telephone operating companies, and capacitance means 506. In the embodiment illustrated herein, the output terminal of each activatable switch means R'l R'8 is coupled to a leased telephone line by series connected resistance means 505a 505k and capacitance means 506a 506h, respectively. It is understood that suitable coupling means such as that described in aforementioned US. Pat. application Ser. No. 165,455 may be interposed between each of the capacitance means 506a 506h and a corresponding leased telephone line. Activatable switch means R9 and R'10 are ac. coupled to corresponding acoustic coupling means by series connected resistance means 505i and 505j and capacitance means 506i and 506j. It is understood that although FIG. 5 illustrates receive station selecting means 204 as being comprised of 10 activatable switch means, it should be clearly understood that any convenient number of activatable switch means may be utilized in accordance with the number of remote facsimile transceivers that are employed. In addition, the output terminal of each activatable switch means may be coupled to a leased telephone line or to an acoustically coupled telephone line if so desired. For purposes of explanation, however, it will be assumed that activatable switch means R9 and Rl0 are dedicated for use with acoustically coupled telephone lines.

The output terminal of amplifying means 504 is additionally coupled to the common connected input terminals of limiter means 507 and 508. Each of limiter means 507 and 508 may be comprised of conventional limiting devices adapted to convert a signal admitting of sinusoidal characteristics to a signal admitting of rectangular wave shape. Such devices are well known in the prior art and need not be further described. The output terminal of limiter means 507 is coupled to the demodulator of the local facsimile transceiver. The output terminal of limiter means 508 is coupled to amplifier means 703 included in the data detecting means illustrated in more detail in FIG. 7.

The data signal receive means 202 of FIG. 2 is comprised of a plurality of limiter means 509a 509j. The input terminal of each limiter means is coupled to a corresponding junction formed by the series connection of resistance means 505a 505j and capacitance means 506a 506j. Accordingly, limiter means 509a is coupled to the junction formed by resistance means 505a and capacitance means 506a. Similarly, limiter means 50% is coupled to the junction formed by resistance means 505b and capacitance means 5061). The

remaining limiter means are similarly connected such that limiter means 509j is coupled to the junction formed by resistance means 505] and capacitance means 506j. Consequently, each limiter means 509a 509j is ac. coupled to an associated telephone line. The limiter means 509a 509j are similar to aforedescribed limiter means 507 and are adapted to convert a signal admitting of sinusoidal characteristics to a signal admitting of rectangular wave shape. The output terminal of each of limiter means 509a 509j is coupled to transmit station selecting means 203. In addition, those limiter means associated with leased telephone lines are further coupled to respective tone detecting means 510. Hence, the output terminal of limiter means 5090 is additionally coupled to tone detecting means 510a, and so on. Each of tone detecting means 510a is adapted to detect an ac. signal admitting of a predetermined frequency. Accordingly, the tone detecting means may comprise sharply tuned band-pass filter means. The output terminals of the tone detecting means 510a are coupled to the logic circuit further illustrated in FIG. 6. It should be noted that those limiter means associated with acoustically coupled telephone lines are not further coupled to cor responding tone detecting means.

Transmit station selecting means 203 is illustrated as comprising a selective switching device such as a rotary switch identified as SEND I. The rotary switching device includes a plurality of stationary contacts each being coupled to a respective one of limiter means